Or she could have just been a stubborn idiot committing idiocy out of her own ignorance, pride and fear. Which seems far more likely to me; And considering Hawke a human went out of their way to befriend her, shelter her and give her purpose for near on a decade you figure she would be more grateful then to just offhandedly blow him off like their request was nothing.
Personally i think nothing of not helping her complete her idiocy.
Again i really think she has a reduced mental aptitude upon occasion.
It seems more likely to me that performing extensive research on the Eluvian would make Merrill more informed about the artifact than Hawke or Marethari.
I also don't hold it against Merrill for learning blood magic from Audacity (which can likely be learned verbally, since the Orlesian Warden can ask the Baroness to teach him blood magic in exchange for siding with her, and Anders even asks Merrill if she learned it by accident from her own blood) since it's trapped to a Buddha-like artifact, and has been bound to the statute since the Arlathan elves fought the Tevinter humans over a millennia ago at Sundermount (long before Andraste was even alive, in fact).
And given her proficient handling of magic, her ability to handle blood magic without succumbing to it, and her ability to evade the templars for years at the seat of templar power over eastern Thedas, I don't see Merrill as an idiot. Not in the least.
As for Hawke, if the main character is a friend to Merrill (if the protagonist takes that route after meeting her), it doesn't make her beholden to acquiesce to Hawke's demands. Merrill is entitled to her own opinions, and pursuing her own goals in life.